import numpy as np

import matplotlib.pyplot as plt

x = np.linspace(-3,3,50)

y1 = 2*x+1

y2 = x**2

plt.figure()
plt.plot(x,y1)

plt.figure(num=3)
plt.plot(x,y2)
plt.plot(x,y1,color='red',linewidth=1.0,linestyle='--')

plt.xlim((-1,2))
plt.ylim((-2,3))
plt.xlabel('I am x')
plt.ylabel('I am y')

new_ticks = np.linspace(-1,2,5)
print(new_ticks)
plt.xticks(new_ticks)
plt.yticks([-2,-1.8,-1,1.22,3],
           [r'$really\ bad$',r'$bad\ \alpha$',r'$normal$',r'$good$',r'$really\ good$'])

plt.show()
